(1) Field of the Invention
The present invention relates to an aircraft provided with a buoyancy system for a rotary element.
Under such circumstances, the invention lies in the technical field of buoyancy systems enabling an aircraft to ditch, and more particularly an aircraft that includes a rotary element that is liable to impact a liquid surface.
(2) Description of Related Art
The term “rotary element” is used in particular to designate a propulsive propeller, or indeed a tail rotor of an aircraft used for controlling the yaw movement of the aircraft and/or for opposing the torque exerted by a lift rotor on a fuselage, for example.
Such an emergency buoyancy system participates in keeping an aircraft afloat and stable in the event of forced ditching, thereby enabling the occupants of the aircraft to be evacuated. All aircraft for use in missions of transporting people over areas of sea are in principle fitted with such buoyancy systems.
An emergency buoyancy system has floats that are deployed either under the control of the pilot and/or the copilot, or else under automatic triggering, in particular by means of an immersion detector. Such floats may comprise bags that are inflated by deployment means that may be explosive or electrical, for example.
Document WO 2008/054401 discloses a system enabling anti-crash airbags to be inflated, by taking account of the attitude of the aircraft and of it approaching the ground at an excessive speed.
Document U.S. Pat. No. 7,156,033 B2 discloses a buoyancy system associated with inhibit means.
Document FR 1 383 688 describes a helicopter having inflatable floats.
Document CA 2 481 789 suggests using an immersion sensor associated with an acceleration sensor for triggering inflation of a float.
The following documents are also known: U.S. Pat. No. 3,547,377 A, DE 198 20 260 A1, U.S. 2004/226498 A1, and U.S. 2004/129831 A1.
For aircraft having rotary elements, it is preferable to avoid the rotary elements coming into contact with the liquid surface.
With a rotorcraft, a main rotor providing lift and possibly also propulsion is located sufficiently high to minimize any risk of the main rotor interfering with a liquid surface.
In contrast, the rotary element(s) that perform the anti-torque function during the ditching stage, such as propellers or an optionally ducted tail rotor occupy a position that makes it possible they will come into contact with a liquid surface.